What if the element doesn't exist?

In a naive implementation, returning undef, zero, or an empty string from exists will fail dereference, and it would happen at runtime. A reference value that evaluates false, yet returns undef when dereferenced, seems to be required.

That seems to need a tricky sort of special-casing that would affect all dereferences.

Update: BrowserUK points out that dereferencing the return of exists yields undef. That does not pass use strict 'refs';, however. exists currently returns the empty string as false, generating Can't use string ("") as a SCALAR ref while "strict refs" in use at -e line 1..

Update 2: To clarify my point, this idea leads to: 

my %foo;
my $bar = ${exists $foo{'bar'}};

[download]
giving assignment to the value without autovivification. The need to provide a reference which is false in bool context (for campatibility) is the basis for my objection.

After Compline,
Zaxo

In reply to Re: optimization - exists should return a reference by Zaxo
in thread optimization - exists should return a reference by John M. Dlugosz

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